Process of producing silicon carbid.



F. J. TONE. PROCESS OF PRODUCING SILICON GARBD). APPLIUATIONE'ILED Jmmu, 1907.

941,339. Ptented Nqv.23,1909.

I To all whom it may concern:

(UNITED 's'r TEs PATENT OFFICE.

FRANK .1. TONE, or unease FALLS, NEW ronx.

Specification of Letters Patent.

PROGESS OF PRODUCING SILICON GABIBID.

Application filed June 14, 1907. Serial No. 879,034.

. an electric furnace, by means of a resistance-- core of granular or pulverized carbon embedded within and extending longitudinally through thegcharge-body. The specific conductivity of'granular carbon is low and it is necessary to employ a core of considerable diameter to carry the requisite current. The charge is a poor conductor of heat, the temperature-gradient from the core outward is steep and the zone within which silicon carbid is produced is radially narrow. Much heat is lost by radiation and conduction from the outer surface of the productive zone and the thermal efliciency .of the furnace varies inversely as the area of this outer surface. It also varies inversely as the diameter and mass of the resistance-core, which must be raised to a high temperature throughout. In removing the silicon carbid from the furnace portions adjacent to the core are more or less mixed with granular carbon therefrom.

According to thepresent process, the resistance-core of granular carbon is replaced ing loosely connected'at' the angles of the zontal and vertical sections, respectively, I of zigzag. The resistancepieces are preferab y supported by' the charge, in such a manner as to remain in contact not vithstanding settling. of the charge, since separate su ports resting'on the base or floor of the mace afl'ord direct paths for the escape of heat. I

Two constructions which have been found effective are shown in the accompanying drawings, in which:

Figures 1 and 2 are longitudinal horia charged'electric furnace havin a straight core; and, Fig. 3 1s a longitudina horizontal section of a chargedfurnace having a zigzag core. A

These furnaces have the usual end walls 1,

side Walls 2 and floor 3, of firebrick. Terminals 4 coupled to electric mains 5 pass through the end walls contact with the ends of the corebeing made by interposed layers 6 of powdered coke. The charge-mixture, consisting essentially ofsilica and carbon, surrounds the core and fills the furnace.

The core shown in Figs. 1, 2 consists of separate carbon bars or blocks 7 arranged in a substantially straight line between the Patented Nov. 23,1909.

terminals 4 and supported by the: charge,

in which they .are' embedded. Alternate bars are superposed at their ends upon'the intermediate bars, the adjacent surfaces being in direct electrical contact.

. The core shown in Fig. 3 differs from that of Figs. 1, 2 only in that the bars 7 are ar-' ranged in a zigzag line, the ends of the bars crossin at the a les. The resistance of the corg'per unit of furnacedength is thereby increased, correspondingly increasing the energy-capacity and output of the furnace without decreasing its thermal efliciency.

The described arrangement of the carbon bars enables them to maintain contact with each other and with the terminals notwithstanding the settling of the charge which ocours as reduction proceeds. All of the heat from the core is transmitted to the charge, and the mass of the core and radiating surface of the product are greatly decreased. The silicon carbid is of better quality, is free from adherent carbon andis more abundantly and'cheaply produced than by the use of a. ranular core.

'sistan'ce-con'ductor consisting of a series of Separate shaped resistance-pieces of predeterminedcross-section and resistance arranged longitudinally in direct electrical contact and supported by the charge, and passing an electric current through said conductor. I

3. The process of producing silicon carbid, which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a series of separate shaped resistance-pieces of predetermined cross-section and resistance loosely and directly connected and so arranged as to maintain contact notwithstanding lateral movement of the conductor, and passing an electric current through said conductor.

4. The process of producing silicon carbid,

which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a series of separate shaped resistance-pieces of predetermined cross-section and resistance loosely and directly connected, supported by the charge, and arranged to maintain contact notwithstanding movement of the charge, and passing an electric current through said conductor.

5. The process of producing silicon carbid, which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a series of separate shaped resistance-pieces arranged longitudinally in direct electrical contact and disposed in a circuitous line between the terminals of the furnace, and passing an electric current through'said conductor.

6. The process of producing silicon carbid, which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a series of separate shaped resistance-pieces arranged longitudinally in direct electrical contact and disposed in a zigzag line between the terminals of the furnace, and passing an electric current through said conductor.

7. The process of producing silicon carbid, which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a series of separate shaped resistance-pieces arranged longitudinally in direct electrical contact and disposed in a zigzag line between the terminals of the furnace, the resistancepieces being loosely connected at the angles of the zigzag, and passing an electric current through said conductor.

8. The process of producing silicon carbid, which consists in embedding in a charge of silicious and carbonaceous materials a resistance-conductor consisting of a'series of separate shaped resistance-pieces arranged longitudinally in direct electrical contact and disposed in a zigzag line between the terminals of the furnace, the resistance pieces being loosely connected at the angles of the zigzag and being supported by the charge, and passing an electric current through said conductor.

In testimony whereof, I affix my signature in presence of-two witnesses.

FRANK J. TONE.

Witnesses:

FRED I. PIERCE, CHARLES CHoRMANN. 

